1 // Copyright Louis Dionne 2013-2017
2 // Distributed under the Boost Software License, Version 1.0.
3 // (See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
5 #include <boost/hana/at.hpp>
6 #include <boost/hana/at_key.hpp>
7 #include <boost/hana/back.hpp>
8 #include <boost/hana/ext/std/tuple.hpp>
9 #include <boost/hana/front.hpp>
10 #include <boost/hana/integral_constant.hpp>
14 namespace hana = boost::hana;
18 T const& cref(T& t) { return t; }
20 // a non-movable, non-copyable type
23 RefOnly(RefOnly const&) = delete;
24 RefOnly(RefOnly&&) = delete;
28 struct RefOnly_i : hana::int_<i> {
29 RefOnly_i() = default;
30 RefOnly_i(RefOnly_i const&) = delete;
31 RefOnly_i(RefOnly_i&&) = delete;
35 std::tuple<RefOnly> t;
37 // Make sure that we return the proper reference types from `at`.
39 RefOnly&& r1 = hana::at_c<0>(std::move(t));
40 RefOnly& r2 = hana::at_c<0>(t);
41 RefOnly const& r3 = hana::at_c<0>(cref(t));
43 (void)r1; (void)r2; (void)r3;
46 // Make sure we return the proper reference types from `front`.
48 RefOnly&& r1 = hana::front(std::move(t));
49 RefOnly& r2 = hana::front(t);
50 RefOnly const& r3 = hana::front(cref(t));
52 (void)r1; (void)r2; (void)r3;
55 // Make sure we return the proper reference types from `back`.
57 RefOnly&& r1 = hana::back(std::move(t));
58 RefOnly& r2 = hana::back(t);
59 RefOnly const& r3 = hana::back(cref(t));
61 (void)r1; (void)r2; (void)r3;
64 // Make sure we return the proper reference types from `at_key`.
66 std::tuple<RefOnly_i<3>> t{};
67 RefOnly_i<3>& r1 = hana::at_key(t, RefOnly_i<3>{});
68 RefOnly_i<3> const& r2 = hana::at_key(cref(t), RefOnly_i<3>{});
69 RefOnly_i<3>&& r3 = hana::at_key(std::move(t), RefOnly_i<3>{});
71 (void)r1; (void)r2; (void)r3;